Liquid crystal displays (LCDs) may be either directly driven or multiplexed. In directly driven LCDs, each segment or element has its own driver. In multiplexed LCDs, one driver drives a number of elements. For multiplexed LCDs having large numbers of elements, a matrix arrangement is commonly used, the matrix consisting of rows and columns of conductors having elements disposed at the intersection of each row and column conductor. The row and column conductors are energised by multiple level driving waveforms. The voltage levels of the waveforms are chosen according to the upper and lower transmission voltage threshold values of the liquid crystal and are conveniently generated by a resistive potential divider. This allows the voltage levels to be adjusted in step with each other by adjusting the voltage which is applied across the potential divider, e.g. by hand tuning. Such adjustment is required for initially setting up the display. Temperature-compensated LCDs are known, in which a temperature - dependent voltage source is included having a linear temperature voltage characteristic. Such temperature compensation gives acceptable performance over a limited temperature range, for example -5.degree. to 45.degree. C. If it is desired to operate over a wider range, it would be possible in principle to produce a voltage source having a non-linear temperature characteristic matching that of the display, but such a source would be considerably more complex and expensive than one having a linear characteristic, and would require calibration over the temperature range.
Another disadvantage of a temperature--controlled voltage source is that the temperature responsive element is in general somewhat remote from the display panel and has a different time--response under rapid changes of temperature. This means that until the temperature has stabilised, the contrast and legibility of the display will be degraded.